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Pressure Systems, Inc. NetScanner™ System (9016, 9021, & 9022) User’s Manual
www.PressureSystems.com
6 - 7
! The module’s calibration valve is not placed in the correct position before executing
the Span calibration command (Calculate & Set Gain). This command will not
automatically shift the valve to the CAL position before taking data (as the Re-zero
calibration command does). The user must manually control the calibration valve
position using the Set Operating Options (‘w’) command if the CAL and CAL REF
inputs are to be used.
! The Re-Zero calibration command (Calculate & Set Offsets) will automatically shift
the calibration valve unless the option is disabled with the Set Operating Options
(‘w’) command. The valve will be placed in the CAL position (with a small delay)
before taking Re-zero data. Afterwards, the valve will be placed in the RUN
position.
! Zero (offset) and Span (gain) correction terms are not automatically saved in
transducer nonvolatile memory. If they are not saved using the Set Operating
Options (‘w’) command, they will be lost when module power is turned off. Verify
that new coefficients produce valid data before saving them.
! When Span calibrating a multi-range unit, attach the calibration pressures to the
individual measurement input ports of the range being calibrated and not to the CAL
input port. Use of the common CAL input may result in over-pressuring lower range
channels. When sending the Calculate and Set Gain (‘Z’) command, ensure that the
position field bits are set only for those channels that are attached to the calibration
pressure.
! When using the standard Calculate and Set Gain (‘Z’) command, the module
firmware assumes, by default, that each particular transducer’s full-scale pressure is
present at its pneumatic/hydraulic input. All internal calculations of gain correction
are based on the exact full scale pressure being applied to the transducers. If it is not
possible to provide this exact pressure (as when using a dead weight tester), the
alternate form of this command should be used. This allows the host to specify the
exact upscale pressure applied to the transducers being calibrated.
! When using the standard Calculate and Set Offsets (‘h’) command, the module
firmware assumes, by default, that each particular transducer’s zero pressure is
present at its pneumatic/hydraulic input. All internal calculations of zero correction
are based on an input pressure of 0.0 psi. If it is not possible to provide this exact
pressure (as when calibrating an absolute pressure transducer), the alternate form of
this command should be used. This allows the host to specify the exact minimum
pressure applied to the transducers being calibrated.